The present invention relates to control of emissions from Ocean Going Vessels (OGVs) at berth or anchored in port and in particular to the collection of exhaust gases inside the OGVs to allow subsequent processing.
OGVs at berth or anchored in port are a significant source of air pollution from the exhaust gases of their auxiliary power sources. The OGVs have auxiliary diesel engines and auxiliary boilers which normally remain in operation while the OGV is at berth or anchored. The auxiliary engines drive generators which provide power for ballast and other pumps, onboard motors, shipboard lighting and air conditioning, communications equipment, and other housekeeping functions. The auxiliary boilers are used to keep the bunker fuel used to feed the main engines warm. If allowed to cool, this fuel becomes so viscous it is difficult or impossible to pump. Heat from the boilers is also used for other shipboard functions.
The boilers and auxiliary engines are a source of nitrogen dioxide (NOx), sulfur dioxide (SOX), particulate matter (PM), and volatile organic compounds (VOCs), all of which are air pollutants. Left untreated, the OGVs are one of the most significant sources of air pollution in the vicinity of ports throughout the world.
The OGVs discharge the exhaust from the auxiliary engines and auxiliary boilers through exhaust pipes clustered within an exhaust stack which runs from the engine room up through the OGV's decks and continues some distance above the top deck. U.S. Pat. No. 7,258,710 for Maritime Emissions Control System, assigned to the assignee of the present invention, describes a maritime emissions control system which may be transported by barge or vessel to an OGV near or within a harbor. The maritime emissions control system uses a bonnet (or umbrella-like device) which is lifted up above the top of the OGV exhaust stack and then lowered over the entire exhaust stack of the OGV and sealing around the exhaust stack perimeter, thereby capturing exhaust otherwise released to the environment. The '710 patent further discloses processing the exhaust flow from the OGV to reduce emissions.
The top of the stack is usually the highest part (other than antennas) of the OGV. A tall crane is therefore required to reach the top of the stack, which adds expense, and requires a skilled and certified crane operator.
Another issue with connecting to the top of the stack is that the connection operation is very difficult to carry out by personnel locally at the stack because of dangers of hot exhaust and pipes, toxic fumes, and limited accessibility at best. Therefore, connection to the stack requires remote control from a distance, using either line of site from another part of the vessel or using video cameras. This remote operation adds cost and complexity to the operation.
Another issue is higher winds at the top of the stacks which makes the connection more difficult. A device hanging from a crane, or other placement device, many tens of feet above ground or sea level, and often over 100 feet above ground or sea level, is frequently subjected to wind forces which cause the attachment system to sway with relatively large excursions, creating a danger of hitting and damaging antennas or other nearby OGV structures. This movement also makes alignment and attachment to the stack difficult if not impossible in windy conditions.
Another drawback is that the exhaust gas must be ducted all the way to the ground, which adds cost and this ducting has to be supported by some means as it makes its way to ground level where the processing equipment is located. This additional duct length adds cost in material for the duct itself and operating cost due to increased pressure drop.
U.S. patent application Ser. No. 12/772,520 filed May 3, 2010 by the present applicant describes a system including a manifold and individual ducts for connecting to the OGVs exhaust pipes for capturing the OGV exhaust. While the system of the '520 application overcomes some of the difficulties of the '710 patent, there remains a need to connect to the original exhaust pipes which is not always convenient, must be performed at a very high point on the OGV, and requires lengthy ducting. The '710 patent and the '520 application are herein incorporated in their entirety by reference.